National Park Service
U.S. Department of the Interior

Natural Resource Stewardship and Science

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Vegetation monitoring site within the Wet Forest Plant Community at Hawaiʻi Volcanoes National Park.

Figure 1: Vegetation monitoring site within the Wet Forest Plant Community at Hawaiʻi Volcanoes National Park.

Background

The Pacific Island Inventory and Monitoring Network (PACN) monitors five vegetation community types across the national parks of the pacific islands. Plant communities (restricted to locations within national park units) include the wet forest of Hawaiʻi and American Samoa, the subalpine shrubland of Hawaiʻi on the slopes of Mauna Loa and Haleakalā, the coastal strand of Hawaiʻi, the limestone forest on the island of Guam, and the mangrove forest on the island of Saipan. Long-term, standardized monitoring protocols (Ainsworth et al. 2011, 2012) are implemented at repeated intervals (5-7 year cycles) to determine the status and trends of these plant communities.

Protocols

  • PACN’s primary vegetation monitoring protocol is titled Focal Terrestrial Plant Communities (FTPC). This protocol utilizes 20m X 50m plots (except in coastal strand communities where plots are 10m X 20m). Native and non-native plant composition and structure are assessed in terms of vascular plant species diversity, understory cover, species density (of woody species by height or size class), and species distribution frequency. Additional measurements are collected on canopy height and coarse woody debris (Ainsworth et al. 2011).

  • Additional data regarding non-native plant species are collected via PACN’s Established Invasive Plant Species (EIPS) protocol. This protocol utilizes 5m-wide transects divided into contiguous sub-plots (segments). Transect length is 1000m in the wet forest (except Kahuku in HAVO) and 500 m in the subalpine shrubland, while segments along the transects are 5m x 20m. At Coastal Strand, Mangrove Forest, and Kahuku-wet forest plant communities, transect length is variable (250m at Kahuku) and segments are 5m x 10m. Non-native species presence and estimates of cover are collected at each segment and summarized across each transect to provide data on non-native plant richness, frequency, and cover (Ainsworth et al. 2012).

Both vegetation monitoring protocols utilize a split panel design with two panels: (1) permanent sites (fixed) that are reread each sampling cycle and (2) temporary sites (rotational) that are visited only once. This design allows for the use of fixed sites to detect temporal changes and rotational sites to assess status and increase spatial coverage over time. (fixed plots/transects are displayed as blue, while rotational plots/transects are displayed as red; Figure 2).

Study Site

Provide background information regarding the selected plant community type including location, elevation, rainfall, unique aspects, etc.

Figure 2: Prior monitoring sites within the ʻŌlaʻa - Wet Forest Plant Community. The community plots (squares) and non-native transects (cirle with line) monitored within the ʻŌlaʻa - Wet Forest Plant Community. Fixed plots = blue; Rotational plots = red.

Methods

Sample Size

  • Plots:

    • Fixed: Olaa: 2010 [n = 12], 2015 [n = 15], 2021 [n = 15]

    • Rotational: Olaa: 2010 [n = 7], 2015 [n = 15], 2021 [n = 14]

  • Transects:

    • Fixed:

    • Rotational:

Understory Cover: Plant species understory cover was sampled within 50 x 20 m plots. Two height layers were recorded: 0-1 m from ground (Low) and 1-2 m from ground (High). Cover data was collected using the pole-intercept method (Ainsworth et al. 2011).

Invasive Plant Transects: Additional data on non-native plants were collected using frequency of occurrence along 500 m transects (Ainsworth et al. 2012).

Results

Understory - Species Composition

  • Narrative descriptions as needed (Figure 3).

  • Additional areas to highlight in narrative.

Average understory species cover across the monitoring area from the most recent monitoring event (2021). Click on a section of the sunburst plot to drill down and click in the center to go back to the previous level of data.

Figure 3: Average understory species cover across the monitoring area from the most recent monitoring event (2021). Click on a section of the sunburst plot to drill down and click in the center to go back to the previous level of data.



--CURRENTLY USING ZONE DATA FOR THIS FIGURE--Average understory species cover across the monitoring area by management unit and monitoring cycle.

Figure 4: –CURRENTLY USING ZONE DATA FOR THIS FIGURE–Average understory species cover across the monitoring area by management unit and monitoring cycle.

Understory - Total Cover

Community Level

  • (Figure 5).
Total native and non-native cover from 2015-2021 (Mean +/- 95% CI). Means in this figure include both fixed plots and rotational plots, so differences between years may be due to spatial variability of the rotational plots. High = Understory 1-2 m; Low = Understory 0-1 m.

Figure 5: Total native and non-native cover from 2015-2021 (Mean +/- 95% CI). Means in this figure include both fixed plots and rotational plots, so differences between years may be due to spatial variability of the rotational plots. High = Understory 1-2 m; Low = Understory 0-1 m.




Plot Level

  • Describe overall picture of native vs. non-native cover across all plots.

  • Describe plots of high or low non-native cover, if appropriate (Figure 6).

  • Describe the magnitude of difference between plots, if appropriate.

Native and non-native understory cover by plot for all monitoring years. Points represent individual monitoring plots (fixed and rotational). Perecent cover is measured as species hits per point and can be greater than 100% because more than one species can be counted at each point. Diagonal grey line represents an even ratio of native cover vs. non-native cover. Use the 'Year' checkboxes to select specific monitoring years.

Figure 6: Native and non-native understory cover by plot for all monitoring years. Points represent individual monitoring plots (fixed and rotational). Perecent cover is measured as species hits per point and can be greater than 100% because more than one species can be counted at each point. Diagonal grey line represents an even ratio of native cover vs. non-native cover. Use the ‘Year’ checkboxes to select specific monitoring years.




Compare understory between two plots:




Understory - Difference in Cover

Community Level

  • (Figure 7).
Mean difference in native and non-native cover when comparing a selected year to the previous monitoring cycle year (Mean +/- 95% CI). High = Understory 1-2 m; Low = Understory 0-1 m.

Figure 7: Mean difference in native and non-native cover when comparing a selected year to the previous monitoring cycle year (Mean +/- 95% CI). High = Understory 1-2 m; Low = Understory 0-1 m.

Plot Level

  • Highlight particular plots with high/low amount of change (Figure 9).

  • Additional Highlights if needed.

  • Hover over a point in the graph to see it highlighted on the map. Double click anywhere in the graph to deselect.

Difference in native and non-native understory cover by plot for all monitoring years. Points represent individual monitoring plots (fixed and rotational). Perecent cover is measured as species hits per point and can be greater than 100% because more than one species can be counted at each point. Difference is calculated by subtracting the first monitoring from the last monitoring cycle. Colored parts of the graph represent shifts in native vs. non-native cover (e.g. red quadrat = increase in non-native cover with concurrent decrease in native cover)

Figure 8: Difference in native and non-native understory cover by plot for all monitoring years. Points represent individual monitoring plots (fixed and rotational). Perecent cover is measured as species hits per point and can be greater than 100% because more than one species can be counted at each point. Difference is calculated by subtracting the first monitoring from the last monitoring cycle. Colored parts of the graph represent shifts in native vs. non-native cover (e.g. red quadrat = increase in non-native cover with concurrent decrease in native cover)

Presence/Absence

Proportion of plots in which a species was present during a monitoring year. Values are listed for the first and last monitoring year, while the trend line in the middle includes all monitoring years. “All Plots” includes both fixed and rotational plots, while fixed plots include only the “fixed” plots that do not change locations. The following list shows the number of plots (n) monitored for each year, displayed as YEAR = [All n, Fixed n]: 2010 = [19, 12]; 2015 = [30, 15]; 2021 = [30, 15].

Figure 9: Proportion of plots in which a species was present during a monitoring year. Values are listed for the first and last monitoring year, while the trend line in the middle includes all monitoring years. “All Plots” includes both fixed and rotational plots, while fixed plots include only the “fixed” plots that do not change locations. The following list shows the number of plots (n) monitored for each year, displayed as YEAR = [All n, Fixed n]: 2010 = [19, 12]; 2015 = [30, 15]; 2021 = [30, 15].




Invasive Plant Transect Data

Non-native Species

Non-Native Cover (Total)

Non-Native Richness

Tree Data

# 1-3 graphs & 1-3 tables 

1. Total Native vs. Non-native Basal Area
2. Change in Native & Non-native Basal Area
3. Basal Area total & change for a particular species of interest (site specific). 

(not appropriate for all sites - for example, no Trees in Haleakala subalpine)

Shrub / Tree-fern / Vine Data

# 1-3 graphs & 1-3 tables 

1. Count/ha of Native vs. Non-native 
2. Change in count/ha of Native & Non-native 
3. Particular species of interest (site specific).

Summary

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